I will never forget the moment a 13-year-old Syrian boy sat in front of me in my office. He couldn’t understand why his sister wasn’t able to join him and the rest of his family here in the UK.

He recounted to me – with a smile on his face – the days before the war in Syria when his sister would wake him each morning, get him ready for school, help him with his homework, and then kiss him goodnight.

Usman Aslam is a solicitor specialising in immigration and asylum law at McGlashan MacKay in Glasgow.

Then he looked me in the eyes and said: “The only way I can say ­goodnight to my sister now is by looking at a photograph of her on my mother’s phone and kissing it.”

His parents told me that every time the phone rang they would think “that’s it, they’ve been hit by a bomb or a bullet”.

This experience reinforces to me why the law on reuniting refugee families in the UK desperately needs to change and why I support Oxfam’s campaign for this to happen.

On Friday 16 March next year, MPs will debate a Private Members Bill proposed by Scottish MP Angus ­MacNeil which could enable more refugees to be reunited here in the UK. It’s the opportunity of a lifetime for the families affected.

Currently, a refugee who has reached the UK is only entitled to apply for their partner, and their children who are under the age of 18, to join them. However, if the child instead makes the treacherous ­journey to the UK on their own, then – as the law stands – the child is not entitled to be reunited with their parents.

Beyond this, the law also separates refugees from their children who are aged over 18, their brothers, ­sisters, parents and grandparents; all of whom may be left alone in hostile environments.

The Home Office amended their Family Reunion Policy in July 2016. On the face of it, this appeared to many as a welcome and long-awaited change, designed to account for the harrowing situation in war zones such as Syria.

Why then do they continue to enforce such restrictive rules? Where applications for family reunion are denied, it remains possible to appeal the decision and to bring it to court. However, that process takes, on average, between eight to 12 months. People in war zones like Syria or Iraq are lucky to make it to the end of the week.

Reams of case law show there is a clear need to make family reunification easier and judges of the highest courts have criticised the family reunion rules.

International law is also clear. When states, including the UK, adopted the UN Refugee Convention in 1951, they stressed in their final act that the unity of the family is an essential right of the refugee.

The UN Convention on the Rights of the Child also imposes specific obligations on states in family reunification cases that involve children. It requires states to protect children against separation from their parents against their will.

In the end, I won the case of the ­Syrian boy and his three sisters were able to rejoin their family here in the UK. But that should never have been in doubt and others continue to face spending this festive season separated from their loved ones.

I have recently presented an appeal to a judge about another child whose parents remain stranded in Syria. The boy told me of his nightmares about what is happening to his ­parents. He says he may decide to cross dangerous territories into war zones just to be with them.

His psychologist has told me she thinks he could be suicidal. But, as it stands, the law says he is not ­entitled to be reunited with his parents in the UK.

We cannot allow such situations to continue to unfold. That’s why I’m supporting Oxfam’s call for all MPs from Scotland and across the UK, including all those who claim to stand up for family values, to turn up when the Bill on family reunion is debated. Lives depend on it.